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Biomedical subjects

A Maeda

Publications and source records attributed to A Maeda.

At least 361 records · Page 20Linked to original sources
PubMed1982

Absorption spectral properties of acetylated bacteriorhodopsin in purple membrane depending on pH.

The dark-adapted form of bacteriorhodopsin in the purple membrane of Halobacterium halobium changes its absorption maximum from 560 to 600 nm if the pH is lowered to about 2 [Oesterhelt, D., & Stoeckenius, W. (1971) Nature (London), New Biol. 233, 149; Moore, T. A., Edgerton, M. E., Parr, G., Greenwood, C., & Perham, R. N. (1978) Biochem. J. 171, 469; Mowery, P. C., Lozier, R. H., Chae, Q., Tseng, T.-W., Taylor, M., & Stoeckenius, W. (1979) Biochemistry 18, 4100; Fischer, U., & Oesterhelt, D. (1979) Biophys. J. 28, 211; Muccio, D. D., & Cassim, J. Y. (1979) J. Mol. Biol. 135, 595]. We compared the pH dependence of the absorption spectra of acetylated membrane with that of unacetylated native membrane. The completely acetylated membrane showed a midpoint of pH 4.8 for the conversion to the acidic form; that of the native membrane was 3.4. On acetylation, the absorption maximum at neutral pH moved from 560 to 555 nm with about 20% decreases in extinction coefficients as compared with that of the native membrane, whereas the spectrum in acid was not affected. The chloride-dependent blue shift from the acidic form of the acetylated membrane was largely suppressed. The CD spectrum of the acetylated membrane was composed of two bands of an opposite sign with slightly decreased amplitudes. The chromophore of the acetylated membrane was sensitive to hydroxylamine, and the spectrum before bleaching was restored on addition of all-trans-retinal to the bleached membrane followed by dark incubation. Blue light irradiation accelerated the conversion to the acidic form in the native membrane but not in the acetylated membrane. Reductive ethylation did not affect the pH dependence of the absorption spectra.

Acetylation↗
PubMed1982

Topological location and biological significance of phospholipids in the membrane of Newcastle disease virus. Hydrolysis of phospholipids in intact virion with pure phospholipases A2, C, and D.

The composition, topological distribution and biological significance of phospholipids in the membrane of Newcastle disease virus (NDV) grown in embryonated chicken eggs were investigated. Phosphatidylethanolamine and sphingomyelin were the predominant phospholipids in NDV membrane. The location of phospholipids in the lipid bilayer of the membrane was studied by assessing their reactivities with highly purified phospholipase A2 (Agkistrodon halys blomhoffi) and phospholipase D (Streptomyces chromofuscus), and the biological role of membrane phospholipids was also investigated by using pure phospholipases A2, C (Bacillus cereus) and D. Choline-containing phospholipids were found predominantly in the outer layer of the membrane. The inner layer was composed mainly of aminoglycerophospholipids, though a fair amount of them also appeared to be located in the outer half of the bilayer. When intact virion was treated with phospholipase C, marked decreases in hemolytic activity and infectivity mediated by viral fusion (F) glycoprotein were observed, but hemagglutinating and neuraminidase activities did not change significantly. Apparently complete hydrolysis of phospholipids in the outer half of the lipid bilayer with phospholipase D caused about 22% decrease in the original hemolytic activity. On the other hand, when all phosphatidylcholine and aminoglycerophospholipids in the outer half of the viral membrane were hydrolyzed with purified phospholipase A2, no significant change in viral hemolytic activity or morphology was detected. No marked change of hemagglutinating and neuraminidase activities was detected on treatment of NDV with phospholipases A2 and D. The above results suggest that the integrity of fatty acid ester of glycerophospholipids in NDV membrane is not essential for the manifestation of viral activities, though polar groups of the phospholipids in the outer half of the membrane may be involved in the function of fusion (F) glycoprotein, but not in that of hemagglutinating and neuraminidase (HN) glycoprotein of NDV.

Hydrolysis↗
PubMed1982

Trial of split-product trivalent influenza vaccine in high-risk children.

Split-product trivalent influenza vaccine, containing H3N2, H1N1 and B, was given to 188 high-risk children and 25 healthy ones in the 4 year period from 1978 to 1981. A field trial involving 80 of these children was performed for evaluating the safety and immunogenicity of this vaccine. The antibody response to influenza vaccine in the patients was similar to that in normal children. The reaction to this vaccine of high-risk children was low, and no severe clinical reactions were observed after vaccination.

Antibody Formation↗
PubMed1982

[Parenteral administration of diphenylhydantoin in the pre- and post-operative course on plasma level measurement].

In the neurosurgical care, postoperative convulsion, the especially in the early postoperative course, is one of major complications because it can spoil an otherwise good surgical result. The present study was intended to investigate the prophylactic use of anticonvulsants on chemical measurement of their plasma levels. Parenteral diphenylhydantoin (DPH) given just before craniotomy failed to maintain high level of DPH in the postoperative course even with pretreatment of oral DPH. On the other hand, preoperative oral phenobarbital administration maintained fairly high level in spite of no prescription on the operative day. Intravenous DPH of 250 mg immediately after craniotomy resulted in fairly high level of DPH throughout the early postoperative course in cases of pretreatment of oral DPH. In reviewing the pharmacokinetics of anticonvulsants, the prophylactic use of anticonvulsants in the early postoperative course was discussed.

Adult↗
PubMed1981

Light-induced reaction of halorhodopsin prepared under low salt conditions.

1. Membrane fraction containing halorhodopsin was prepared from the lysate of a mutant strain of Halobacterium halobium, Y1, which is defective in bacteriorhodopsin synthesis. 2. Irradiation of the membrane with red light at 0 degrees C decreased the absorbance intensities over the whole range of 500--600 nm and a new absorption peak appeared at about 400 nm. This process was reversed either by irradiation with blue light or simply by incubation in the dark. The wavelength at which the red light-induced absorbance decrease became maximum was 566 nm in the absence of NaCl and moved to 576 nm upon addition of NaCl. The midpoint for the conversion was at about 0.1 M NaCl. 3. Even though the membrane containing halorhodopsin was prepared in the absence of NaCl, this pigment was photochemically active in the sense that it could form a bathochromic photoproduct, a batho-intermediate, at -196 degrees C. 4. Retinal isomer composition during irradiation with red light at 0 degrees C was determined. Unirradiated halorhodopsin had predominantly all-trans retinal. With the increase of the blue-shifted product on irradiation, 13-cis content increased.

Bacteriorhodopsins↗